Cable stripping tool

ABSTRACT

A hand tool suitable for cutting the insulation jacket on &#34;Romex&#34;-type cables. The tool is adapted to cut the insulation jacket crosswise and lengthwise so that the cable sheath may be removed with a slight pull. The tool includes a pair of handles which are hinged at one end. The opposite end of one of the handles includes a pair of blades which are spaced apart and which &#34;slice&#34; across the cable sheath and then pass clear the cable when the handles are squeezed together. A pair of slitting blades located within the handles engage the insulation on the remaining opposite sides of the cable. The tool is then drawn down the length of the cable away from the original cut to complete the operation.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates generally to hand tools and, inparticular, to a new and novel cable stripping tool.

(2) Description of the Prior Art

It is the general practice in the construction industry to stripinsulation from electrical cables and wires by cutting or scrapingusually with a pocket knife. However, in cables having an outer plasticsheath and two or more insulated, stranded or solid wires, there is adanger of knicking or otherwise damaging the insulation on the innerwires. This method is slow and time-consuming, requires a certain degreeof skill before becoming proficient, and often results in irritatingcuts to the user's fingers. In addition, this method is even moredifficult when there is a need to strip a cable inside of confinedspaces, such as light switch and receptacle boxes.

U.S. Pat. No. 2,054,973 to Ferguson discloses a tool for strippinginsulation from electrical wires. The Ferguson tool is a plier-like toolwhich allows an increase in the mechanical advantage over a simplehandle-type. A first cut is made in the insulation surrounding thestranded or solid wire with the semi-circular cutting edges of a pair ofopposed circular cutters. The cutters then stay in contact with theinsulation as the tool is drawn away from the cut to strip theinsulation from the wire. This has a tendency to "bunch up" theinsulation, thereby increasing the amount of force necessary to removethe insulation. This can result in damage to the stranded or solid wire.In the preferred embodiment, the Ferguson tool includes a pair ofside-slitting blades which have a tapered lead-in for slitting the sidesof the insulation.

U.S. Pat. No. 4,594,921 to Ishmael discloses a coaxial cable strippingtool in which a pair of blade-shaped heating elements are clampedagainst opposite sides of the cable and the cable rotated to form acircumferential cut in the insulation. The cable is then placed inanother jig with a V-shaped groove therein and a second blade-shapedheating element at the bottom of the groove. A second similar heatingelement is arranged above the groove in the cable. The two heatingelements then produce diametrically opposed longitudinal cuts in theinsulation, after which the two pieces of cable insulation can beremoved. The circumferential cut requires that the cable and tool berotated with respect to one another. In addition, the cable must bephysically removed from the jig before the blades are free of theconductors.

The Kaufman patent (U.S. Pat. No. 3,881,248), Bradley patent (U.S. Pat.No. 3,180,184), and Sibley patent (U.S. Pat. No. 698,567) are allexamples of other cross-cutter type stripping tools. However, like theabove patents, all these patents teach a "chopping-cutting" arrangementin which, after cutting opposite sides of the conductor, the bladesremain in contact with the insulation while the insulation is removed.Furthermore, this cutting arrangement requires a different opening sizefor each size cable in order to prevent damage to the wires inside thecable.

It has thus become desirable to develop a cable stripping tool that willeasily remove the outer plastic sheath of the cable in a confined spacesuch as a light switch box while, at the same time, prevent damage toinsulation on the inner stranded or solid wire by either bunching up theinsulation or otherwise stressing the inner stranded or solid wires suchas by conventional "chopping" type strippers. Furthermore, the toolshould be able to cut more than one side of cable without damaging thewires inside the cable.

SUMMARY OF THE INVENTION

The present invention solves the aforementioned problems associated withthe prior art by providing a hand tool suitable for cutting theinsulation jacket on "Romex"-type cables which is adapted to cutcrosswise and lengthwise so that the cable sheath may be removed with aslight pull after using the tool. The tool includes a pair of handleswhich are hinged at one end and biased outwardly by a spring. Theopposite end of one of the handles includes a pair of blades which arespaced apart and which "slice" across the cable sheath when the handlesare squeezed together. Thus, in operation, the cable is first positionedbetween a pair of opposed guides adjacent to the blades at a point wherethe cable sheath is to be removed. The handles are then squeezedtogether with one hand which makes tangential slices on the oppositesides of the insulation perpendicular to the length of the cable. Thepair of blades are substantially rigidly mounted but are somewhatflexible with respect to one another, thereby permitting the tool to beused on more than one cable size. After making these cuts, the slicingblades continue and pass clear the cable.

In the preferred embodiment, a pair of slitting blades located withineach of the guides engage the insulation on the remaining oppositesides. The tool is then drawn down the length of the cable away from theoriginal cut to complete the operation. Thus, the present tooleliminates the worry of cutting hands or fingers with the conventionalknives or blades while eliminating damage to the stranded or solid wirescaused by bunching or otherwise stressing the inner stranded or solidwires.

Accordingly, one aspect of the invention is to provide a tool forstripping insulation or sheathing from a cable having at least oneconductor. The tool includes a pair of jaws adapted to move from an openposition to a closed position, means for scoring the insulation orsheathing on opposite sides, and a pair of oppositely mounted cuttingblades. The blades are removably mounted to the jaws along thelongitudinal axis of the cable and adjacent to the cable and are adaptedto make longitudinal slits in the insulation or sheathing of the cablewhen the jaws are closed.

Another aspect of the present invention is to provide a cutting assemblyfor a tool for stripping insulation or sheathing from a cable. Theassembly includes a pair of opposed, substantially rigidly mountedcutting blades which are mounted at a predetermined distance withrespect to one another. The assembly also includes means for moving thepair of opposed, substantially rigidly mounting cutting blades from anopen position to a position where the blades are moved in tangentialpath, contacting opposite sides of the cable, continuing through atleast a portion thereof, and passing clear of the cable, thereby scoringthe insulation or sheathing on opposite sides.

Still another aspect of the present invention is to provide a hand toolfor stripping insulation or sheathing from a cable having at least oneconductor. The tool includes a pair of jaws adapted to move from an openposition to a closed position, a pair of oppositely mounted cuttingblades removably mounted to the jaws along the longitudinal axis of thecable and adjacent to the cable which are adapted to make longitudinalcuts in the insulation or sheathing of the cable when the pair of jawsare closed, a pair of opposed, substantially rigidly mounted cuttingblades which are mounted at a predetermined distance with respect to oneanother, and means for moving the pair of opposed, substantially rigidlymounted cutting blades from an open position to a position where theblades are moved in a tangential path, contacting opposite sides of thecable, continuing through at least a portion thereof, and passing clearof the cable.

These and other aspects of the present invention will be more clearlyunderstood after review of the following description of the preferredembodiment of the invention when considered along with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cable stripping hand tool inaccordance with the present invention.

FIG. 2 is an enlarged exploded perspective view of the jaw assembly ofthe hand tool shown in FIG. 1.

FIGS. 3 and 4 are end views illustrating the operation of the hand toolof FIG. 1.

FIG. 5 illustrates how the outer insulating cable sheath can be easilyremoved after being sliced and slit by the hand tool in FIG. 1.

FIG. 6 is a perspective view of an alternative embodiment of a hand toolaccording to the present invention.

FIG. 7 is an enlarged top view of the wire stripper shown in FIG. 1.

FIG. 8 is an enlarged sectional view taken along line 8--8 of FIG. 4illustrating the slicing blade arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in general and to FIG. 1 in particular, itwill be understood that the illustrations are for the purpose ofdescribing a preferred embodiment of the invention and are not intendedto limit the invention thereto. As best seen in FIG. 1, a cablestripper, generally designated 10, is shown in accordance with thepresent invention. Cable stripper 10 somewhat resembles a pair of icetongs, includes a pair of handles which are formed into jaws 12 and 14.Jaws 12,14 are connected at one end by means of a pivot joint 16 and arebiased apart by spring 18. Construction of pivot joints 16 is such as topermit the jaws to swing partially open but only so and an inoperativeposition with respect to a cable (not shown). Cable stripper 10 includesa slicing means 20 having a pair of opposed blades 22 and spaced apart apredetermined amount with respect to one another depending on the sizeof the cable which is being utilized. In addition, each jaw 12,14includes a pair of U-shaped guide grooves 24 for receiving andpositioning the cable. Guides 24 include a pair of opposed slittingblades 26 located adjacent to and transverse to guides 24. Attachmentmeans 37 secure the slicing means 20 and a blade guard 28 to jaws 12,14and permit their removal and replacement. Jaws 12,14 include an abutmentportion 30 located towards pivot joint 16 for preventing the operator'shand from slipping when the tool is utilized. In the preferredembodiment, a portion of one of jaws 12,14 also includes a strippingmeans 32 for removing the insulation of the inner stranded or solidwires after the outer layer of the cable has been stripped.

As used herein, "slicing" refers to cuts made in the sheath of the cableperpendicular to the axis of the cable; "slitting" refers to cuts madein the sheath which runs along the axis of the cable; and "stripping"refers to the process of removing the outer insulating sheath from thecable. As used herein, a cable is defined as having a plurality ofindividual strands or solid wires, at least some of which have an outerlayer of insulation and which the entire bundle of wires are surroundedby a outer insulating sheath or jacket.

Turning now to FIG. 2, there is shown an enlarged exploded perspectiveview of the jaw assembly of the hand tool shown in FIG. 1. Each of jaws12,14 include a slit 34 aligned along the longitudinal axis of jaws12,14 and adapted to receive slitting blades 26. Jaws 12,14 includeU-shaped abutments 36 which butts against three sides of slicing means20 and guard 28 and, in combination with attachment means 37, preventsany movement of the assemblies with respect to the jaws. The relativedimensions of the guard 28 and slicing means 20 are such as to preventthe removal of slitting blades 26 from slits 34 after assembly. In thepreferred embodiment, slitting blades 26 also each include a notch 38located along the length of blade 26 and adapted to receive end of pinmeans 39 when the stripper 10 is assembled, thereby further interlockingthe assemblies.

As can be best seen in FIGS. 3 and 4, there is shown the operation ofthe hand tool of FIG. 1 removing the outer insulating sheath from a"Romex"type cable 40 having a pair of insulated leads 44,46 and agrounding wire 48. As can be seen, slitting blades 22 cut tangentiallyalong opposite surfaces of cable 40 as the jaws 12,14 of tool 10 aresqueezed together. Guides 24 positions and prevents the downwardmovement of cable 40. In the preferred embodiment, abutments 52 contactthe surface of cable 40 and limit the cutting depth of slicing blades22, thereby allowing different cable sizes to be cut with the sameblades. Once slicing blades 22 have cut across cable 40 and continue andpast clear of cable 40, slitting blades 26 also engage the surface ofthe sheath 42 of cable 40 and cut thereinto. With jaws 12,14 heldtogether, the user then pulls tool 10 along the remaining length ofcable 40 causing slitters 26 to penetrate the outer plastic insulatingsheath 42 of the cable 40. However, as discussed above, slicing blades22 are no longer in contact with the surface of the cable 40, therebypreventing bunching of the insulation.

As best seen in FIG. 5, a sliced and slit outer insulating sheath 42 isshown of cable 40 after the operation of tool 10 in accordance with thepresent invention. As shown, the outer insulating sheath 42 is stillattached to the main cable body 40 along portions designated "A".However, the area "A" represents a relatively small portion of the outerinsulation sheath 42 and the excess portions of the sheath can be easilyremoved by pulling firmly or simply pulled back out the way.

Turning now to FIG. 6, there is shown a perspective view of analternative embodiment of a hand tool in accordance with the presentinvention. While the operation of this tool is essentially the same asdescribed above, in the tool shown as FIG. 6 jaws 14 are extended toform handles 50,51, respectively. A plier-type pivot joint 54 is locatedtowards cutting blades 22,26, thereby increasing the mechanicaladvantage which the user can assert when stripping cable 40. Inaddition, the ends of handles 50,51 are turned upward and outward toform a pair of abutments 56 for preventing the slippage of user's handwhen the tool is operated.

As best seen in FIG. 7, the tool 10 may include a stripping means 32which can be utilized to remove the insulation from the insulated leads44,46. Stripping means 32 includes a flat plate 60 having a pair ofkeyhole-shaped openings 62. The larger portion of the keyhole-shapedopenings 62 is sized to receive the insulated leads 42,44. The smallerportion of the keyhole-shaped openings 62 includes a blade surface 64which is sized to cut through the insulation of conductors 42,44 but notto damage the inner stranded or solid wire. A pair of openings 66 permitthe attachment of stripping means 32 to either of jaws 12,14 and permitits removal and replacement as needed.

Finally, turning to FIG. 8, an enlarged sectional view of the slicingblades is shown. As discussed above, in the preferred embodiment, eachslicing blade 22 includes an abutment 52 adjacent to the blade and setback from the top of each blade 22. During the slicing operation,abutments 52 contact the surface of cable 40 and limit the cutting depthof slicing blades 22, thereby allowing difference cable sizes to be cutwith the same blades. As can also be seen, guard 28, guides 24 andslicing means 20 cooperate together to prevent cutting hands or fingersand damage to the blades.

Certain modifications and improvements will occur to those skilled inthe art upon reading of the foregoing description. By way of example,the ends of the jaws of the tool could be offset with respect to toolbody to provide additional clearance with respect to the cable whichpermits the insulation from a relatively stiff cable to be removed moreeasily. It should be understood that all such modifications andimprovements have been deleted herein for the sake of conciseness andreadability but are properly within the scope of the following claims.

We claim:
 1. A hand tool for stripping insulation or sheathing from acable having at least one conductor, comprising:(a) a pair of jawsadapted to move from an open position to a closed position; (b) a pairof oppositely mounted cutting blades, said blades being mounted to saidjaws along the longitudinal axis of the cable and adjacent to the cable,said blades being adapted to make longitudinal cuts in the insulation orsheathing of the cable when said pair of jaws are in said closedposition; (c) a pair of opposed, substantially rigidly mounted cuttingblades, said blades being mounted at a predetermined distance withrespect to one another; and (d) means for moving said pair of opposed,substantially rigidly mounted cutting blades from an open position to aposition where said blades are moved in a tangential path, contactingopposite sides of the cable, continuing through at least a portionthereof of the insulation or sheathing, and passing clear of the cable,thereby scoring the insulation or sheathing on opposite sides; wherebythe insulation or sheathing can be removed from the cable.
 2. The toolaccording to claim 1, further including means for positioning the cablewith respect to said pair of oppositely mounted cutting blades.
 3. Thetool according to claim 2, wherein said jaws each include a channelalong the longitudinal axis of the cable and adjacent to the cable forreceiving said cutting blades.
 4. The tool according to claim 2, whereinsaid means for positioning the cable with respect to said pair ofoppositely mounted cutting blades are removably mounted to a portion ofsaid jaws adjacent to said channel for receiving said pair of oppositelymounted cutting blades, whereby said means for positioning the cable,said channels, and said cutting blades are interlocked to secure saidcutting blades in said channels.
 5. The tool according to claim 1,wherein said jaws are integrally formed into a pair of handles.
 6. Thetool according to claim 5, wherein said pair of handles are pivotedlymounted together and include means for returning said jaws to said openposition from said closed position.
 7. The tool according to claim 1,further including means for positioning the cable with respect to saidpair of opposed, substantially rigidly mounted cutting blades.
 8. Thetool according to claim 1, wherein said predetermined distance isgreater than the width of the conductor and less than the width of theinsulation or sheathing.
 9. The tool according to claim 1, wherein saidmeans for moving said pair of opposed, substantially rigidly mountedcutting blades include means for returning said cutting blades to saidopen position.
 10. A tool for stripping insulation or sheathing from acable having at least one conductor, comprising:(a) a pair of jawsadapted to move from an open position to a closed position; (b) meansfor contacting opposite sides of the cable, continuing through at leasta portion thereof of the insulation or sheathing, and passing clear ofthe cable, thereby scoring the insulation or sheathing on opposite sidesof the cable; and (c) a pair of oppositely mounted cutting blades, saidblades being mounted to said jaws along the longitudinal axis of thecable and adjacent to the cable, said blades being adapted to makelongitudinal cuts in the insulation or sheathing of the cable when saidpair of jaws are in said closed position;whereby the insulation orsheathing can be removed from the cable.
 11. The tool according to claim1, further including means for positioning the cable with respect tosaid pair of oppositely mounted cutting blades.
 12. The tool accordingto claim 1, wherein said jaws are pivotedly mounted together and includemeans for returning said jaws to said open position from said closedposition.
 13. The tool according to claim 10, wherein said jaws eachinclude means aligned with the longitudinal axis of the cable andadjacent to the cable for receiving and securing said cutting blades.14. A cutting assembly for a tool for stripping insulation or sheathingfrom a cable having at least one conductor, comprising:(a) a pair ofopposed, substantially rigidly mounted cutting blades, said blades beingmounted at a predetermined distance with respect to one another; and (b)means for moving said pair of opposed, substantially rigidly mountedcutting blades from an open position to a position where said blades aremoved in a tangential path with respect to the cable, contactingopposite sides of the cable, continuing through at least a portionthereof of the insulation or sheathing, and passing clear of the cable,thereby scoring the insulation or sheathing on opposite sides;wherebythe insulation or sheathing can be removed from the cable.
 15. The toolaccording to claim 14, further including means for positioning the cablewith respect to said pair of opposed, substantially rigidly mountedcutting blades.
 16. The tool according to claim 14, wherein saidpredetermined distance is greater than the width of the conductor andless than the width of the insulation or sheathing.
 17. The toolaccording to claim 5, wherein said means for moving said pair ofopposed, substantially rigidly mounted cutting blades from an openposition to a position where said blades are moved in a tangential pathwith respect to the cable, includes a pair of jaws adapted to move froman open position to a closed position, said jaws being pivotedly mountedtogether and including means for returning said jaws to said openposition from said closed position.